Preparation and Characterization of Collagen-GAGs Bioactive Matrices for Tissue Engineering

Collagen materials were crosslinked by 1-ethyl-3-(3-dimethyl aminopropyl) carbodiimide (EDC) in the presence of chondroitin sulfate (CS), one of glycosaminoglycans (GAGS). PVA and chitosan were also blended with collagen. The physical and chemical properties of the matrices were characterized by SEM, DSC, and ESCA. L929 cells were implanted on the matrices to show the cytotoxic and the biological characters of the materials. The results indicate that EDC is an effective and non-cytotoxic cross-link reagent, which can replace the common dialdehyde reagent. The attachment of CS can improve the stability of collagen and accelerate cell growth. The addition of PVA can prepare porous matrices with smaller bore size. There are reactions between the chitosan and collagen, and the composite has good biological character. The presence of chitosan can also increase the amount of incorporated CS.

Ultrasound Speckle Reduction Based on Histogram Curve Matching and Region Growing

The quality of ultrasound scanning images is usually damaged by speckle noise.This paper proposes a method based on local statistics extracted from a histogram to reduce ultrasound speckle through a region growing algorithm.Unlike single statistical moment-based speckle reduction algorithms,this method adaptively smooths the speckle regions while preserving the margin and tissue structure to achieve high detectability.The criterion of a speckle region is defined by the similarity value obtained by matching the histogram of the current processing window and the reference window derived from the speckle region in advance.Then,according to the similarity value and tissue characteristics,the entire image is divided into several levels of speckle-content regions,and adaptive smoothing is performed based on these classification characteristics and the corresponding window size determined by the proposed region growing technique.Tests conducted from phantoms and in vivo images have shown very promising results after a quantitative and qualitative comparison with existing work.

DYNAMIC OPTICAL COHERENCE ELASTOGRAPHY:A REVIEW

With the development of optical coherence tomography,the application optical coherence elastography(OCE)has gained more and more attention in biomechanics for its unique features including micron-scale resolution,real-time processing,and non-invasive imaging.In this review,one group of OCE techniques,namely dynamic OCE,are introduced and discussed including external dynamic OCE mapping and imaging of ex vivo breast tumor,external dynamic OCE measurement of in vivo human skin,and internal dynamic OCE including acoustomotive OCE and magnetomotive OCE.These techniques overcame some of the major drawbacks of traditional static OCE,and broadened the OCE application fields.Driven by scientific needs to engineer new quantitative methods that utilize the high micron-scale resolution achievable with optics,results of biomechanical properties were obtained from biological tissues.The results suggest potential diagnostic and therapeutic clinical applications.Results from these studies also help our understanding of the relationship between biomechanical variations and functional tissue changes in biological systems.

EFFECTS OF SPECTRAL DEPENDENCE IN PASS-THROUGH PHOTON-BASED BIOMEDICAL TRANSILLUMINATION

We have proposed an interferometric setup for biomedical analysis in transillumination modality.Wavelength dependence of optical properties must be considered for selecting source and sample.An expansion of the sample optical properties,around the central wavelength of emission,serves to account for spectral effects.Expected spectral values depend on the central moments of the source,and specific constants associated to the optical properties of the sample.By matching wavelength characteristics of source and sample,a first-order approximation is applicable.In such case,the expected values are exactly the optical properties evaluated at the central wavelength.Furthermore,in the first-order approximation,the transillumination interferometer yields the integrated attenuation of the sample at the central wavelength of emission.We verify the latter assertion by performing a wavelength-dependent Monte Carlo analysis to calculate the response of the transillumination interferometer.Recovered attenuation coefficients,for imaging and characterization scenarios,are in agreement with the value computed at the central wavelength of the source.

Ultrasonic spectrum characterization of pig's pathological liver tissues

A high-speed digital acquisition and wide-band measurement system was used to acquiring and recording the ultrasonic pulse waveforms backscattered from normal and several pathological pig's fresh liver tissues (including ballooning degeneration, fatty degeneration, cirrhosis) in vitro. Some frequency-domain analyses were performed in which integrated backscattering coefficient (IBSC), frequency dependence of backscattering coefficient (FDBSC),and mean spacing (MS) among adjacent scatterers of the tissues were determined.In the experiments the frequency domain was from 3MHz to 7 MHz. The obtained results show that the differences among normal and various pathological tissues cause distinct changes of the measured parameters. The results show that the ultrasonic spectum technique, which can be used in tissue characterization for pathological liver in clinical, has an exciting prospect.

Purification and characterization of growth stimulating diadenosine triphosphate from porcine myocardial tissue

The proliferationof vascular smooth muscle cells (VSMC) plays a role in the maintenance of hypertension and atherosclerosis. Diadenosine polyphosphates have been identified as modulators of the cardiovascular system. We detected the existence of diadenosine polyphosphates in the heart and studied their growth stimulating effect on VSMC. Porcine cardiac tissue was deproteinated with perchloric acid and concentrated with a preparative reversed phase C18 column. Then the extract was separated with a size exclusion column, an anion exchange column, and an affinity column. It was then chromatographed with an anion exchange HPLC and a reversed phase HPLC and a purified substance was obtained. Med. Klinik I, Nephrol. Labor, Univ. Klinik Marien hospital, University of Bochum, Herne, Germany (Luo JK, Wang H, Schlüter H, JankowskifJ, Potthoff W, Tepel M and Zidek W) Using the BrdU method, this substance was shown to have a growth stimulating effect that is dose-dependent on VSMC. Matrix assisted laser desorption/ionization mass spectrometry (MALDI MS) analysis showed that the molecular mass of the substance was 757.0, the same as diadenosine triphosphate (AP 3A). UV spectrum indicated the maximum absorption at 259 nm, similar to that of adenosine. Postsource decay (PSD) MALDI MS showed that the substance contained adenine, adenosine, AMP, ADP, and ATP, respectively. Enzymatic cleavage revealed that phosphates in this molecule connected adenosine in 5' position. It was determined from the above data that the substance was Ap 3A. In this study the existence of Ap 3A was demonstrated in the heart. It has a growth stimulating effect on VSMC.